Method and system for monitoring vibration of robots in an automated storage library

ABSTRACT

A method and system for the storage and retrieval of media in an automated storage library having media storage cells each housing a single media includes a robotic mechanism. The robotic mechanism is operable to move through the storage library to access the media in the media storage cells. A vibration sensor is associated with the robotic mechanism for generating a vibration signal indicative of vibration of the robotic mechanism. A controller is operable with the vibration sensor for processing the vibration signal to determine if the vibration of the robotic mechanism is abnormal. In the event that the vibration is abnormal, the controller generates a warning signal to warn the operator of the storage library of a possible problem prior to actual failure of the robotic mechanism. The controller is also operable to associated the vibration of the robotic mechanism with particular storage library locations to warn the operator of possible problem locations of the storage library.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation of co-pending application Ser. No.09/584,639 filed on May 31, 2000.

TECHNICAL FIELD

[0002] The present invention relates generally to robotic mechanismsthat manipulate media cartridges in an automated media cartridge storagelibrary system and, more particularly, to a method and system formonitoring vibration of robotic mechanisms in an automated storagelibrary to warn of storage library failure events.

BACKGROUND ART

[0003] It is a problem in an automated media cartridge storage libraryto provide an early warning of failure events such that the failureevents can be addressed before they prevent down time of the storagelibrary. Existing automated storage libraries are capable of storing andretrieving large quantities of information stored on media cartridges.This is accomplished by the use of a large number of cartridge storagecells, each of which houses a single media cartridge, that are housedwithin an enclosure. Such storage libraries use a robotic mechanism orpicker to quickly move the media cartridges between their mediacartridge storage cells and media cartridge players. For example, toretrieve information that is stored on a selected media cartridge, arobotic mechanism is moved to a location opposite the media cartridgestorage cell that houses the selected media cartridge. An end effectorof the robotic mechanism then grasps the media cartridge and extracts itfrom the media cartridge storage cell to a media player where the endeffector loads the media cartridge into the media player.

[0004] A typical storage library includes tracks laid out throughout thestorage library. Robotic mechanisms are mounted to the tracks to movethroughout the storage library to access the media cartridges and themedia cartridge player. The location of the robotic mechanisms in thestorage library may be monitored as they move on the tracks through thestorage library. A problem occurs when a robotic mechanism or a portionof the track degrades or fails. For instance, a defective roboticmechanism may not be able to access the media cartridges or move throughthe storage library. A defective robotic mechanism unable to move andstuck on a track may impede movement of other robotic mechanisms alongthe track. A robotic mechanism may not be able to traverse a defectivetrack portion and consequently be unable to reach a selected mediacartridge or media cartridge player.

[0005] Robotic mechanisms mounted on tracks use rotatable componentssuch as wheels to move along the tracks and other movable componentssuch as an end effector for moving the media cartridges in and out ofthe storage cells. During operation the components of the roboticmechanisms have vibration characteristics and other parametersassociated with their movements. When the robotic mechanisms areoperating properly the vibration characteristics match known vibrationcharacteristics indicative of proper operation. When the roboticmechanisms are not operating properly due to such factors as wear,misuse, accidental damages, and the like the vibration characteristicsdiffer from the known vibration characteristics. Properly operatingrobotic mechanisms also exhibit different vibration characteristics whenmoving over defective tracks. As the robotic mechanisms start to degradethe vibration characteristics start to change. The change of thevibration characteristics is a flag and a warning indicative of roboticmechanisms problems. These problems can be addressed before they becomebigger problems, such as robotic mechanism failure, by monitoring thevibration characteristics of the robotic mechanisms to become aware ofthe warnings and act on them.

SUMMARY OF THE INVENTION

[0006] Accordingly, it is an object of the present invention to providea method and system for monitoring robotic mechanism vibration in anautomated storage library to warn of storage library failure events.

[0007] It is another object of the present invention to provide a methodand system for monitoring robotic mechanism vibration in an automatedstorage library to detect robotic mechanism degradation or failure.

[0008] It is a further object of the present invention to provide amethod and system for comparing robotic mechanism vibrationcharacteristics in an automated storage library to known roboticmechanism vibration characteristics indicative of proper operation todetect robotic mechanism degradation or failure.

[0009] It is still another object of the present invention to provide amethod and system for monitoring robotic mechanism vibration of arobotic mechanism moving on a track throughout an automated storagelibrary to detect track degradation or failure.

[0010] It is still a further object of the present invention to providea method and system for monitoring robotic mechanism vibration in anautomated storage library to perform selected diagnostic routines inresponse to certain robotic mechanism vibration characteristics.

[0011] In carrying out the above objects and other objects, the presentinvention provides an automated storage library having a plurality ofmedia storage cells each housing a single media. A robotic mechanism isoperable to move to access the media in the media storage cells. Avibration sensor is associated with the robotic mechanism for generatinga vibration signal indicative of vibration of the robotic mechanism. Acontroller may be operable with the vibration sensor for processing thevibration signal to determine if the vibration of the robotic mechanismis abnormal.

[0012] In carrying out the above objects and other objects, the presentinvention further provides a method for operating an automated storagelibrary having a plurality of media storage cells each housing a singlemedia. The method includes moving a robotic mechanism to access themedia in the media cells. Vibration of the robotic mechanism is thenmonitored. A vibration signal indicative of the vibration of the roboticmechanism is then generated. The vibration signal may then be processedto determine if the vibration of the robotic pod is abnormal.

[0013] The advantages associated with the present invention arenumerous. The method and system of the present invention sensemechanical vibrations in a robot assembly and correlate the sensory datato a normal data pattern to provide an early warning of impendingfailure. By placing a vibration sensor (accelerometer) on board a movingrobotic assembly, and using the electrical output of the vibrationsensor to feed a logic circuit, a system of checks against knownparameters of the robotic pod and the storage library could be used togauge whether the mechanics are running smoothly.

[0014] The above objects and other objects, features, and advantages ofthe present invention are readily apparent from the following detaileddescription of the best mode for carrying out the present invention whentaken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 illustrates a perspective view of an automated librarysystem in accordance with the present invention;

[0016]FIG. 2 illustrates a side view of a robotic pod of the automatedlibrary system in accordance with the present invention; and

[0017]FIG. 3 illustrates a flow chart describing operation of the methodand system of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

[0018] Referring now to FIG. 1, an automated storage library 100 for usewith the present invention is shown. Storage library 100 includesmultiple independent robotic mechanisms (robotic pods) 102 to enablelibrary system 100 to concurrently manipulate multiple media cartridges105. Storage library 100 includes a two-dimensional vertical standingarray of media cartridge storage cells 103 and media cartridge players104 that are mounted in a frame 101. A system of tracks or rails 121-126is used to guide robotic pods 102 through all of the locations in thearray. Robotic pods 102 contain a movable carriage that is capable oftransporting robotic components, such as media cartridge pickers, barcode reading devices, and other task oriented sub-modules on tracks121-126 of storage library 100.

[0019] Frame 101 is designed to receive a plurality of rows 151-155 ofmedia cartridge storage cells 103 each of which is designed to house asingle media cartridge 105. Media cartridge players 104 are shown in anarbitrary location in a horizontal row 155 at the bottom of frame 101,although storage library 100 can incorporate media cartridge players 104at any location in frame 101 to optimize performance. Robotic pods 102are attached to frame 101 via horizontal guide tracks or rails 121-126which serve to frame media cartridge storage cells 103 and mediacartridge players 104 on the top and bottom sides thereof. Storagelibrary 100 includes an array of media storage cells 103 fully populatedwith media cartridges 105 of any arbitrary type. Robotic pod tracks121-126 provide support of robotic pods 102 in the vertical direction tooppose the force of gravity, and they also provide a meshing surface ofa suitable design to impart traction in the horizontal direction formotive transport of the robotic pods. Robotic pods 102 each incorporatea drive means for propulsion in the horizontal direction along guidetracks 121-126.

[0020] Storage library 100 further includes vertical elevator assemblies131-133 that enable the transfer of robotic pods 102 in the verticaldirection. Each of vertical assemblies includes a set of vertical rails142 that extend substantially from the top of frame 101 to the bottom ofthe frame. Vertical rails 142 support elevator stations 140 each ofwhich contain short horizontal track segments 141A, 141B that areidentical in cross section to the main horizontal guide tracks 121-126.Elevator stations 140 are held in suspension by drive belts 143 whichwrap around a respective drive pulley attached to a respective verticaldrive motor 111-113. When a vertical displacement is required of anyrobotic pod 102, vertical elevator 140 is scheduled to move in alignmentto the appropriate level of rows 151-155 to allow transfer of therobotic pod onto the elevator track segments 141A, 141B from the pair ofhorizontal tracks 121-126 that are juxtaposed and abutting to elevatortrack segments 141A, 141B. Once robotic pod 102 is located on elevatorstation 140, drive motor 113 is activated to transport robotic pod 102to a selected one of rows 151-155 and thence moves on to the pair ofhorizontal tracks 121-126 that correspond to the selected row.

[0021] A storage library control unit (controller) 160 provides commandsto robotic pods 102 and elevator stations 140 to manipulate mediacartridges 105. Controller 160 communicates with each robotic pod 102individually by radio frequency communication links, infraredcommunication links, or other wireless links. Wired communication linksmay be use if only a few robotic pods 102 are used in storage library100 and their paths are simple to keep the wires from becoming entangledwith each other. Commands to robotic pods 102 include movement alongtracks 121-126, movement of media cartridges 105 into and out of therobotic pods, reading bar codes on the media cartridges, and the like.

[0022] Controller 160 and robotic pods 102 are operable with one anothersuch that the controller knows the position of the robotic pods withinstorage library 100 as they move about tracks 121-126. This isaccomplished by mounting position sensors on robotic pods 102 whichprovide information regarding the position of the robotic pods tocontroller 160. This may also be accomplished by providing sensors ontracks 121-126 which are actuated to transmit a signal to controller 160when a robotic pod 102 traverses a sensor on tracks 121-126. This mayfurther be accomplished by having robotic pods 102 provide informationregarding the speed and direction of their travels through storagelibrary 100.

[0023] Communications between controller 160 and elevator motors 111-113is typically provided by direct wiring. Commands from controller 160 toeach of elevator motors 111-113 include at least moving elevators 140 upand down and holding the elevators in position. Each elevator motor111-113 is controlled independently of the other elevator motors.

[0024] Controller 160 may also be in communication with media cartridgeplayers 104. In one embodiment, controller 160 provides commands tomount and dismount media cartridges 105 into and out of media cartridgeplayers 104. Controller 160 coordinates these commands with positioningcommands to a robotic pod 102 that supplies or receives a mediacartridge 105 to and from a media cartridge player 104. In anotherembodiment, an external source (not shown) provides the mount anddismount commands directly to media cartridge players 104. Here,controller 160 coordinates with the external source to position theproper robotic pod 102 adjacent media cartridge player 104 prior to themount or dismount command being given to the media cartridge player.

[0025] Referring now to FIG. 2, a side view of a robotic pod 102supported on an upper track 121 and a lower track 122 (both shown inphantom) is shown. Robotic pod 102 has a frame 162 for structuralsupport. Frame 162 is suspended from upper track 121 by multiple maindrive wheels 164 that ride in a main groove 166 provided in upper track121. Additional wheels 168 and 170 are rotatably mounted in frame 162.These additional wheels 168 and 170 move in additional grooves 172 and174 provided in upper track 121 and lower track 122 respectively. Theadditional wheels 172 and 174 help orient robotic pod 102 with respectto media cartridge storage cells 103 and media cartridge players 104.

[0026] Main drive wheels 164 are coupled to a drive mechanism 176. Drivemechanism 176 rotates main drive wheels 164 to cause robotic pod 102 tomove along tracks 121-122. An electronics circuit 178 coupled to drivemechanism 176 provides control over the speed and direction of maindrive wheels 164. Electronics circuit 178 is operable to communicatewith controller 160 for controlling robotic pod 102 and providinginformation regarding the robotic pod to the controller.

[0027] Robotic pod 102 further includes a gripper mechanism 180. Grippermechanism 180 is operable to move to an extended position to grasp amedia cartridge 105 and to move back to a retracted position to pull themedia cartridge into robotic pod 102 to enable transportation of theselected media cartridge to a designated location by the movement of therobotic pod.

[0028] In accordance with the present invention, robotic pod 102 furtherincludes a vibration sensor 182 for sensing mechanical vibration of therobotic pod during its operation. Vibration sensor 182 is preferably anaccelerometer or the like operable with electronics circuit 178 forcommunicating with controller 160. Vibration sensor 182 is operable tosense vibration associated with rotation of main wheels 164 and supportwheels 168 and 170, vibration associated with operation of drivemechanism 176, vibration associated with operation of gripper mechanism180, and the like. Vibration sensor 182 is capable of sensing vibrationamplitude and frequency and vibration patterns and combinations thereof.

[0029] Referring now to FIG. 3, a flowchart 200 describing operation ofthe method and system for monitoring vibration of robotic pods in anautomated storage library to warn of storage library failure events inaccordance with the present invention is shown. Vibration sensor 182monitors vibration of robotic pod 102 as the robotic pod moves throughstorage library 100 as shown in block 202. Vibration sensor 182 may alsomonitor vibration of robotic pod 102 as it interacts with mediacartridges 104 as described above. Vibration sensor 182 generates avibration signal indicative of vibration of robotic pod 102 as therobotic moves or operates as shown in block 204. Vibration sensor 182provides the vibration signal to electronics circuit 178 which forwardsthe vibration signal to controller 160. A position signal indicative ofthe position of robotic pod 102 is also generated in one of the mannersdescribed above as the robotic pod moves through storage library 100 asshown in block 206. The position signal is also forwarded to controller160.

[0030] Controller 160 processes the vibration signal to determine theamplitude and the frequency of the vibration of robotic pod 102 as shownin block 208. Controller 160 also stores the vibration signal and theposition signal in a memory as shown in block 210. Controller 160 thenprocesses the stored vibration and position signals to determinevibration patterns of robotic pod 102 and to associate storage librarylocations with the vibration patterns as shown in block 212. Controller160 then compares the monitored vibration amplitude and frequency torespective vibration amplitude and frequency thresholds with controllogic as shown in block 214. The vibration and amplitude frequencythresholds define a border between proper and improper operation ofrobotic pod 102. For instance, if the monitored vibration amplitude islarger than the threshold vibration amplitude then robotic pod 102 isoperating improperly. Likewise, if the monitored frequency falls outsideof a suspect frequency range then robotic pod 102 is acting properly.Controller 160 then compares the monitored vibration pattern to a knownvibration pattern as shown in block 216. The known vibration pattern isindicative of proper or improper operation of robotic pod 102.

[0031] Controller 160 then generates a warning signal if the monitoredvibration amplitude or frequency is different than the respectivethreshold vibration amplitude or frequency as shown in block 218. Thewarning signal is indicative of a possible problem with robotic pod 102.Controller 160 also generates a warning signal indicative of improperrobotic pod 102 operation if the monitored vibration pattern isdifferent than the known vibration pattern.

[0032] Controller 160 generates a warning signal of a possible problemwith a particular storage library location if the monitored vibrationpattern is different than the known vibration pattern at an associatedstorage library location as shown in block 220. Controller 160 may alsogenerate a warning signal indicative of a possible problem with aparticular storage library location if the monitored vibration ofrobotic pod 102 is different at the particular storage library locationwhen compared to the monitored vibration of the robotic pod at othercomparable storage library locations. Robotic pod 102 may have adifferent vibration pattern at an associated storage library locationbecause the storage library is functioning improperly at the associatedlocation. For instance, a segment of track 121 of storage library 100may not be working properly. Similarly, a media cartridge player 104 oran elevator 140 may not be functioning properly. The warning signalsgenerated by controller 160 may differ as a function of the severity ofthe possible problem or the deviance of the measured vibrationcharacteristic with a desired vibration characteristic.

[0033] In response to a warning signal, controller 160 causes an actionto be performed to address possible problems with robotic pod 102 orstorage library 100. The action may include performing a selecteddiagnostic routine in response to a particular type of warning signal oras a function of the severity of the warning signal. The action may alsoinclude generating an alarm to notify a storage library operator ofpossible problems. The method and system of the present invention isparticularly useful in a storage library 100 having multiple roboticpods 102 as controller 160 sorts out the vibration of the variousrobotic pods. Furthermore, in track mounted storage library 100vibration sensors 182 mounted on robotic pods 102 provide exactinformation on which part of which robotic pod or which segment oftracks 121-126 is out of shape. Failure of a wheel or a track segment ishighly undesirable and controller 160 is operable to pick out variousvibration frequencies (and amplitudes) associated with operation ofrobotic pod 102 to notify the storage library operator that the wheelsor track segments need to be replaced before failure actually occurred.

[0034] It is to be appreciated that the robotic mechanism and thestorage library configuration described herein are merely examples of apreferred embodiment of the present invention. Other types of storagelibrary configurations may be employed such as a cylindrical storagelibrary configuration. Other types of robotic mechanisms may be employedsuch as a rotatable robotic arm.

[0035] Thus it is apparent that there has been provided, in accordancewith the present invention, a method and system for monitoring vibrationof robots in an automated storage library to warn of storage libraryfailure events that fully satisfy the objects, aims, and advantages setforth above. While the present invention has been described inconjunction with specific embodiments thereof, it is evident that manyalternatives, modifications, and variations will be apparent to thoseskilled in the art in light of the foregoing description. Accordingly,it is intended to embrace all such alternatives, modifications, andvariations as fall within the spirit and broad scope of the appendedclaims.

What is claimed is:
 1. A storage library having a plurality of mediastorage cells each housing a media, the storage library comprising: arobotic mechanism operable to move to access the media in the mediastorage cells; and a vibration sensor associated with the roboticmechanism for generating a vibration signal indicative of vibration ofthe robotic mechanism.
 2. The storage library of claim 1 furthercomprising: a controller operable with the vibration sensor forprocessing the vibration signal to determine vibration of the roboticmechanism.
 3. The storage library of claim 2 wherein: the controller isfurther operable to generate a warning signal indicative of improperoperation of the robotic mechanism if the vibration of the roboticmechanism is abnormal.
 4. The storage library of claim 2 wherein: thecontroller compares the generated vibration signal to a known vibrationsignal indicative of normal operation of the robotic mechanism todetermine if operation of the robotic mechanism is abnormal.
 5. Thestorage library of claim 2 wherein: the controller compares thegenerated vibration signal to a threshold signal to determine ifoperation of the robotic mechanism is abnormal.
 6. The storage libraryof claim 2 wherein: the controller is operable with the roboticmechanism to know the location of the robotic mechanism as the roboticmechanism moves, wherein the controller associates the vibration signalwith the location of the robotic mechanism to determine if the vibrationof the robotic mechanism is abnormal at a particular location.
 7. Thestorage library of claim 1 wherein: the robotic mechanism is a roboticpod operable to move on tracks to access the media in the media storagecells.
 8. The storage library of claim 7 wherein: the robotic podincludes wheels for rotating on tracks to move the robotic pod to accessthe media in the media storage cells, wherein the vibration sensorgenerates a vibration signal indicative of vibration associated withrotation of the wheels on the tracks.
 9. The storage library of claim 7wherein: the robotic pod includes a drive mechanism for propelling therobotic pod to move the robotic pod to access the media in the mediastorage cells, wherein the vibration sensor generates a vibration signalindicative of vibration associated with propulsion of the drivemechanism.
 10. The storage library of claim 1 wherein: the roboticmechanism includes a gripper mechanism for gripping the media in themedia storage cells, wherein the vibration sensor generates a vibrationsignal indicative of vibration associated with gripping of the media.11. The storage library of claim 1 wherein: the vibration sensor is anaccelerometer mounted to the robotic mechanism.
 12. A storage librarycomprising: a plurality of media storage cells each housing a media;tracks disposed adjacent to the media storage cells for enabling accessto each of the media storage cells; and a robotic pod operable to moveon the tracks to access the media in the media storage cells; and avibration sensor associated with the robotic pod for generating avibration signal indicative of vibration of the robotic pod.
 13. Thestorage library of claim 12 wherein: the robotic pod includes wheels forrotating on the tracks, wherein the vibration sensor generates avibration signal indicative of vibration associated with rotation of thewheels on the tracks.
 14. The storage library of claim 12 furthercomprising: a controller operable with the vibration sensor forprocessing the vibration signal to determine vibration of the roboticpod.
 15. The storage library of claim 14 wherein: the controller isfurther operable to generate a warning signal indicative of improperoperation of the robotic pod if the vibration of the robotic pod isabnormal.
 16. The storage library of claim 14 wherein: the controllercompares the generated vibration signal to a known vibration signalindicative of normal operation of the robotic pod to determine ifoperation of the robotic pod is abnormal.
 17. The storage library ofclaim 14 wherein: the controller is operable with the robotic pod toknow the location of the robotic pod as the robotic pod moves, whereinthe controller associates the vibration signal with the location of therobotic pod to determine if the vibration of the robotic pod is abnormalat a particular location.
 18. A method for operating an automatedstorage library having a plurality of media storage cells each housing amedia, the method comprising: moving a robotic mechanism to access themedia in the media cells; monitoring vibration of the robotic mechanism;and generating a vibration signal indicative of the vibration of therobotic mechanism.
 19. The method of claim 18 further comprising:processing the generated vibration signal to determine vibration of therobotic mechanism.
 20. The method of claim 19 further comprising:generating a warning signal indicative of improper operation of therobotic pod if the vibration of the robotic mechanism is abnormal. 21.The method of claim 19 wherein: processing the generated vibrationsignal includes comparing the generated vibration signal to a knownvibration signal indicative of normal operation of the robotic mechanismto determine if operation of the robotic mechanism is abnormal.
 22. Themethod of claim 19 wherein: processing the generated vibration signalincludes comparing the generated vibration signal to a threshold signalto determine if operation of the robotic mechanism is abnormal.
 23. Themethod of claim 18 further comprising: monitoring the location of therobotic mechanism as the robotic mechanism moves; and associating thegenerated vibration signal with the location of the robotic mechanism todetermine if the vibration of the robotic mechanism is abnormal at aparticular location.